Who Is N.I.S.T.? Every Country has a government body that controls the measurement standards,
and has in its possession the ultimate standards of physical parameters, such
as dimensional parameters, electrical parameters, optical parameters etc.

In the USA,
N.I.S.T. (National Institute
of Standards and Technology) carries out this task ensuring that via correct
calibration all similar instruments measure the same parameter producing the
same reading within their capabilities. The process is very similar to ensuring
that every choirboy sings from the same hymn sheet!